Abd al-Rahman bin Abi Atiq says: I heard my father (say) that he heard Sayyidah Aishah (may Allah be pleased with her) (narrate) that the Prophet (peace and blessings be upon him) said: "The miswak is a cause of purifying the mouth and a means of the Lord's pleasure."
He is Abd al-Rahman bin Abdullah bin Abi Atiq; Yazid attributed him to his grandfather. One view is that Abd al-Rahman narrated it from al-Qasim bin Muhammad, so it is as if he heard it from both of them.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 138